Food-flavoring method and composition using 2-methoxy-3-isobutylpyrazine

ABSTRACT

Leucine amide is reacted with glyoxal to produce 2-hydroxy-3isobutylpyrazine, and this intermediate is methylated to yield the new compound 2-methoxy-3-isobutylpyrazine. This compound exhibits an intense aroma of freshly chopped green bell peppers, and is useful for flavoring food products.

United States Patent 7 2] lnventors Ron G. Buttery Richmond;

Richard M. Seifert, El Cerrito; Robert E. Lundin, Berkeley; Dante G. Guadagni, Moraga, all of Calif.

Apr. 18, 1969 Dec. 28, 1971 The United States of America as represented by the Secretary of Agriculture [21] Appl. No. [22] Filed [45] Patented [73 Assignee [5 4] FOOD-FLAVORING METHOD AND COMPOSITION USING 2-METHOXY-3- ISOBUTYLPYRAZINE 16 Claims, No Drawings [52] [1.8. CI 99/140 R, 260/250 R A231 U22, @9191 1 16...

[50] Field 01 Search 99/1, 23,

28, 54, 59, 86,118, l26,134,136,139,l40 R; 260/250 R [56] References Cited UNITED STATES PATENTS 3,008,832 11/] 961 Gorsica 99/140 3,328,402 6/1967 Winter 99/140 X 3,459,556 8/1969 Moore et al. 99/140 UX Primary ExaminerJoseph Scovronek Assistant Examiner-Barry S. Richman Attorneys-R. l-lofiman, W. Bier and W. Takacs ABSTRACT: Leucine amide is reacted with glyoxal to produce 2-hydroxy-3-isobutylpyrazine, and this intermediate is methylated to yield the new compound 2-methoxy-3-isobutylpyrazine. This compound exhibits an intense aroma of freshly chopped green bell peppers, and is useful for flavoring FOOD-FLAVORING METHOD AND COMPOSITION USING 2-METl-lOXY-3-ISOBUTYLPYRAZINE A nonexclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

DESCRIPTION OF THE INVENTION lam-omen.

OCH N/ a This compound (hereinafter referred to as MlP) exhibits an intense odor typical of freshly chopped green bell pepper, and can be used in minor proportions for flavoring food products such as ketchup, gravies and sauces, vinegar, soups, salad dressings and marinades, cheeses, aspic and other gelled products, pizza mixes and sauces, pilafs, pickles and relishes, crackers, potato chips, corn chips, tortillas, and meat products including sausages, hamburger, meat loaves, stews, hashes, and the like.

In using MIP as a flavoring agent, it is incorporated in the food in the same way as one would incorporate any other flavoring or seasoning agent. Because of its intense flavoring value, MI? is ordinarily employed in a very minor proportion, for example, in a concentration of about 0.00] to 1 part per million. It is obvious, however, that there is nothing critical about the concentration which is used; it is simply a matter of attaining a desired flavor level appropriate to the food in question.

MIP may be added directly to the food-to be flavored, or it may be first incorporated with a diluent to increase its bulk so that small amounts of the compound may be accurately metered into the food. As the diluent, one may use liquid or solid carriers such as water, ethyl alcohol, glycerol, edible fats or oils, starch, sorbitol, salt, sugar, gelatin, flour, citric acid, powdered skim milk, corn syrup solids, or other nontoxic substance compatible with the material to be flavored.

A flavoring composition useful for flavoring meat dishes and in general cookery, may be prepared, for example, by mixing the following ingredients:

MIP, about 0.001 to 1 part Anticaking agent (such as magnesium carbonate, calcium carbonate, calcium phosphate, or calcium silicate), about 1 to 2 parts Sodium chloride, sufl'lcient to give a total of 100 parts.

It is, of course, within the compass of the invention to use MlP in combination with other flavoring agents. For example, one may mix a carrier with MlP and with a known flavoring agent such as monosodium glutamate, onion powder, garlic powder, black pepper, paprika, or dried herbs such as parsley, oregano, celery, sage, and the like.

MlP dissolves readily in water, and a flavoring composition in liquid form may be prepared, for example, by dissolving about 0.001 to 1 part MlP in 1000 parts of sterile distilled water.

We have ascertained that MI? is present in green bell peppers (Capsicum annuum var. Grossum, Sendt) and its presence therein may be demonstrated by procedures of distillation and chromatography. However, it is to be emphasized that prior to this invention MI? was not known to exist in green bell peppers, or elsewhere for that matter.

A particular advantage of the invention is that it enables the provision of MlP in pure form. In this state, MlP has high and uniform flavoring power and is free from extraneous substances, so that it can be advantageously used, even in very minor proportion, for the effective flavoring of food products. In the state in which MlP exists in distillates of green bell peppers, it is too dilute to be effective for flavoring applications. Also, such distillates very widely in the flavor characteristics so that they cannot be depended upon to yield uniformly flavored food products.

Another phase of the invention concerns the salts of MlP. Since MI? is an organic base, it is capable of forming salts. indeed, these salts constitute a valuable form of MIF in that they exhibit low volatility and hence can be kept for long periods of time without loss of MIP. As in the case of other organic bases, the salts of MlP are readily prepared by contacting MlP with an acid. Usually hydrochloric acid is employed, but this is by no means critical and one can use other acids such as sulfuric, phosphoric, acetic, citric, fumaric, tartaric, etc.

When the salt is to be used, the MlP is readily released therefrom by contact with a basic substance such as sodium bicarbonate, sodium carbonate, calcium hydroxide, sodium hydroxide, potassium hydroxide, potassium carbonate, or the like. Alternately, the salts of MlP can be used as such to flavor foods. They are effective in such flavoring applications because MlP is a very weak base, hence is readily freed from its salts on contact with materials having basic or buffering properties such as are normally present in many foods. In utilizing the salts of MIF directly as flavoring agents, they are incorporated into the food to be flavored in the same manner as explained hereinabove in connection with MlP in the free base form. In sum, the salts, as such or in a carrier, are incorporated in the food in the amount which yields the desired flavor. Moreover, flavoring compositions can be formed with the salts just as hereinabove explained with MIP itself.

EXAMPLES The invention is further demonstrated by the following illustrative examples.

EXAMPLE l-SYNTHESIS OF MlP L-Leucine amide (3.9 g.) dissolved in methanol (30 ml.) and water (150 ml.) was cooled to l0 C. Glyoxal di(sodium bisulfite) (8.0 g.) was added to this solution and dissolved by stirring. Sodium hydroxide (3.0 g.) in water (10 ml.) was then added and the mixture stirred for 1 hour, keeping the temperature below l0 C. It was then allowed to warm to room temperature and stirred for 2 more hours. The solution was then neutralized with 12 N hydrochloric acid (3.75 ml.) and taken to dryness under vacuum at 50 C. The solid residue was extracted with boiling chloroform (4X75 ml.). Removal of the chloroform under vacuum gave crystalline 2-hydroxy-3-isobutylpyrazine (3.2 g.). Infrared absorption and mass spectra of this product were consistent with that expected for this structure. A sample recrystallized from ethyl acetate had m.p. -92.5 C.

2-Hydroxy-3-isobutylpyrazine (l.52 g.) in ether (30 ml.) was methylated by addition of a dry ether (75 ml.) solution of diazomethane (about 1 g.), keeping the mixture cooled by an ice bath during the addition and for a further 20 minutes. The mixture was then allowed to warm to room temperature over the next 20 minutes and the excess ether and diazomethane removed on a steam bath to give crude MlP (1.58 g.). Preparative gas chromatography, using a l0-ft. long X IQ-inch O.D. aluminum column packed with methyl silicone oil coated on a diatomaceous support, column temperature 160 C., gave the pure 2-methoxy-3-isobutylpyrazine (0.49 g.). The mass spectrum of this compound (above mass 40, intensities in parenthesis with base peak taken as showed a molecular ion at 166 (3.5), major ions at 124 (100), 41 (21), 94 (20), 151 (16),43 (1l),95 (ll)53 (1l),42(11),93 81 (9), 125 (8). its infrared absorption spectrum (neat, absorption maxima in microns) showed strong maxima at 3.39, 3.43, 3.50, 6.49, 6.85, 6.9, 7.2, 7.7, 8.6, 9.9, medium maxima at 3.28, 3.46, 7.4, 8.4, 9.4, 11.8, and weak maxima at 3.33, 6.34, 7.9, 8.1, 9.2, 10.5, 10.8, 1 1.2, 13.3.

Green bell peppers were chopped and subjected to vacuum steam distillation to recover a volatile oil in a yield of about 1 part per 1,000,000 parts of peppers. The oil was fractionated by GLC. The major component was found by IR and mass spectra to be identical with M1? synthesized as described above.

EXAMPLE 2-AROMA EVALUATION Compound Odor threshold (Pts. per 10" pts. 11,0) M1? 2 Methyl mercaptan 20 fi-lonone 50 2,4-Decadienal 70 2,6-cis-Nonadienal 100 Ethyl 2 methylbutyrate 100 Amyl acetate 2,000 Cinnamic aldehyde 50,000 Benzaldehyde 350,000 Ethyl acetate 500,000

Having thus described our invention, we claim: 1. A method for flavoring a food which comprises adding thereto a minor proportion of pure 2-methoxy-3-isobutylpyrazine.

2. A method for flavoring a food which comprises adding thereto a minor proportion of a salt of 2-methoxy-3-isobutylpyrazine.

3. A composition comprising (a) a major proportion of a food and (b) a minor proportion of added pure 2-methoxy-3- isobutylpyrazine.

4. A composition comprising (a) a major proportion of a food and (b) a minor proportion of a salt of 2-methoxy-3- isobutylpyrazine.

5. A method for flavoring a food which comprises adding thereto a composition containing a. a major proportion of an innocuous carrier, and

b. a minor proportion of 2-methoxy-3-isobutylpyrazine.

6. The method of claim 5 wherein the carrier is water.

7. The method of claim 5 wherein the carrier is a finely divided carbohydrate.

8. The method of claim 5 wherein the carrier is sodium chloride.

9. The method of claim 5 wherein the carrier is ethyl alcohol.

10. A method for flavoring a food which comprises adding thereto a composition containing a. a major proportion of an innocuous carrier, and

b. a minor proportion of a salt of 2-methoxy-3-isobutylpyrazine.

11. A flavoring composition comprising (a) a major proportion of an innocuous carrier, and (b) a minor proportion of 2- methoxy-3-isobutylpyrazine.

12. The composition of claim 11 wherein the carrier is water.

13. The composition of claim 11 wherein the carrier is a finely divided carbohydrate.

14. The composition of claim 11 wherein the carrier is sodium chloride.

15. The composition of claim 11 wherein the carrier is ethyl alcohol.

16. A flavoring composition comprising (a) a major proportion of an innocuous carrier, and (b) a minor proportion of a salt of 2-methoxy-3-isobutylpyrazine.

t t i i 

2. A method for flavoring a food which comprises adding thereto a minor proportion of a salt of 2-methoxy-3-isobutylpyrazine.
 3. A composition comprising (a) a major proportion of a food and (b) a minor proportion of added pure 2-methoxy-3-isobutylpyrazine.
 4. A composition comprising (a) a major proportion of a food and (b) a minor proportion of a salt of 2-methoxy-3-isobutylpyrazine.
 5. A method for flavoring a food which comprises adding thereto a composition containing a. a major proportion of an innocuous carrier, and b. a minor proportion of 2-methoxy-3-isobutylpyrazine.
 6. The method of claim 5 wherein the carrier is water.
 7. The method of claim 5 wherein the carrier is a finely divided carbohydrate.
 8. The method of claim 5 wherein the carrier is sodium chloride.
 9. The method of claim 5 wheRein the carrier is ethyl alcohol.
 10. A method for flavoring a food which comprises adding thereto a composition containing a. a major proportion of an innocuous carrier, and b. a minor proportion of a salt of 2-methoxy-3-isobutylpyrazine.
 11. A flavoring composition comprising (a) a major proportion of an innocuous carrier, and (b) a minor proportion of 2-methoxy-3-isobutylpyrazine.
 12. The composition of claim 11 wherein the carrier is water.
 13. The composition of claim 11 wherein the carrier is a finely divided carbohydrate.
 14. The composition of claim 11 wherein the carrier is sodium chloride.
 15. The composition of claim 11 wherein the carrier is ethyl alcohol.
 16. A flavoring composition comprising (a) a major proportion of an innocuous carrier, and (b) a minor proportion of a salt of 2-methoxy-3-isobutylpyrazine. 